Packaging is one area frequently overlooked in attempts to reduce cleaning time, labor and cost. Hot-melt glues and liquid adhesives are often used in sealing cartons, containers, and other packages. In industrial applications, packaging is completed through automated equipment. The emphasis of these processes and machines is the construction and sealing of packaging in an efficient manner to produce packaging of high structural integrity.
In this context, the emphasis on bonding agent application is often the quantity and strength of the adhesive rather than the accurate delivery and placement of "just enough" bonding agent to avoid spillage.
Excess bonding agent may find its way onto machine surfaces as a result of overspray, spillage, or attempts to apply the adhesive out of sequence in an automated line. The resulting spillage may contact any number of machine surfaces or substrates such as conveyor mechanisms, decking, or framework. These machine surfaces or substrates may comprise any metal, metal-alloy, composite, ceramic, polymeric, or plastic compositions. As a result, during processing, adhesives may deposit and stick onto any number of surfaces during application such as the packaging machine, conveyor equipment, as well as transport and storage equipment. Removal of these adhesives can require extended hot-water sprays of several hours directed at the bonding agents, just to allow for manual scraping. Attempts with much stronger, potentially harmful chemicals get mixed, often poor results.
Various release agents have been known and used before in any number of applications. For example, in the area of foods, Seaborne et al, U.S. Pat. No. 4,874,618 discloses a two-compartment food package separated by an edible barrier useful in the containment of food articles. In the various examples of the patent, the edible barrier comprises food products ground in with various grains and other fillers as well as minor amounts of ingredients such as lecithin, intended to hold the composition together.
Hanson, Jr. et. al, U.S. Pat. No. 4,420,496 discloses a release agent which is useful for frozen food products which are stored in low temperature environments. The Hanson et al release agent may comprise an oil such as almond oil, apricot kernel oil, safflower seed oil, walnut oil, cherry kernel oil, and rapeseed oil combined with lecithin or a lecithin-white mineral oil mixture. The ultimate Hanson, Jr. et al composition is intended to have a viscosity which will allow the composition to maintain a substantial liquid form even when stored at below freezing temperatures.
Clapp et al, U.S. Pat. No. 5,296,021 discloses an aerosol-dispensable foodstuff parting composition. The Clapp et al composition is a water-in-oil emulsion of lecithin or lecithin derivatives and edible oil, as well as an emulsifying agent, water, and a pressurized normally gaseous propellant.
Release agents have also been used in various applications for the manufacture of molded plastics and thermally formed materials. Specifically, a published unexamined Japanese patent application 1-181739 to Sato et al discloses the use of a hydrophilic animal or vegetable lecithin as a release agent for food products and molded plastic materials. Specifically, in Example 9 of Sato et al, a release agent comprising a hydroxylated soybean lecithin, diluted in water, is compared to a lecithin composition diluted in toluene. These two compositions are used as release agents for heat-molded styrene resin products which result from an injection molding apparatus. Sato et al discloses the use of a hydrophilic lecithin dispersed in water for use in food-related applications, as well as industrial applications such as mold release agents.
Additionally, published unexamined Japanese Patent Application 5-309,663 to Kuroda et al discloses a release agent for molding resin products that are environmentally safer and industrially more efficient to use. The Kuroda et al composition preferably comprises a mixture of terpene-type cyclic hydrocarbons such as dipentene, limonene and isoparaffin hydrocarbon oils as well as a minor portion of lecithin.
Silicon-based release agents are also known such as products from Clearko, Inc. and Wesson. While these products tend to have broad applicability, silicon-based compositions tend to film the surface of application and, are generally not food grade.
These compositions and applications do not address the various problems encountered in the area of packaging. In these instances, bonding agents may have to be removed from machinery, conveying equipment, and even packaging materials quickly and efficiently without the use of heat or other agents or conditions which hamper processing. For example, the perishable nature of food requires that any packaging have a high structural integrity to provide for a hermetic seal, strength, and freedom from contamination. Further, the very nature of food, in that it is ultimately intended for consumption, requires that the food not only be kept free from external contamination, but also be kept free from contamination by any elements with which it comes into contact during preparation, packaging, storage and consumption.
Additionally, there is a need in other packaging environments to provide for release of bonding agents without creating deleterious effects on packaging equipment, the articles being packaged, as well as avoiding inefficiencies within the packaging process.